Passivation\nof Perovskite Solar Cells with Natural\nFlavors: Roles of Hydrogen Bonding in Ion Migration and Moisture Resistance

The passivation strategy is considered to be an essential\napproach\nfor enhancing the efficiency and stability of perovskite solar cells\n(PSCs). Herein, based on density functional theory calculations and\nab initio molecular dynamics simulations, we investigated the ion\nmigration and moisture stability for MAPbI<sub>3</sub> passivated\nwith a Lewis base represented by natural molecules: cinnamaldehyde\n(CA) and anethole (AT). The results reveal that hydrogen bonding in\ndifferent forms plays a significant role in both ion migration and\nmoisture stability for surface passivation. The passivation inhibits\nion migration by enhancing intrinsic hydrogen bonding through space\ncompression effect, leading to a boosted activation barrier and a\nreduced rate by up to 3–10 orders of magnitude. Passivations\nprevent in-depth water infiltration and diminish the disturbance of\nthe lattice by water. In addition to the familiar water-shielding\nbehavior, the water-locking effect induced by the intermolecular hydrogen\nbonding chains was observed. The experimental results of durable water\nstability and alleviated hysteresis for passivated PSCs fully confirmed\nthe theoretical study. The established mechanism provides valuable\nguidance to deal with troublesome ion migration and moisture resistance\nin stable and efficient PSCs.